make tests for solution hinting

tests/test_solvers_solhint.py

@@ -0,0 +1,36 @@
+import unittest
+
+import cpmpy as cp
+from cpmpy.exceptions import NotSupportedError
+
+
+class TestSolutionHinting(unittest.TestCase):
+
+
+    def test_hints(self):
+
+        a,b = cp.boolvar(shape=2)
+        model = cp.Model(a ^ b)
+
+        for n, solver_class in cp.SolverLookup.base_solvers():
+            slv = solver_class(model)
+            try:
+                args = {"cp_model_presolve": False} if n == "ortools" else {}  # hints are not taken into account in presolve
+
+                slv.solution_hint([a,b], [True, False])
+                self.assertTrue(slv.solve(**args))
+                self.assertEqual(a.value(), True)
+                self.assertEqual(b.value(), False)
+
+                slv.solution_hint([a,b], [False, True]) # check hints are correctly overwritten
+                self.assertTrue(slv.solve(**args))
+                self.assertEqual(a.value(), False)
+                self.assertEqual(b.value(), True)
+
+                slv.solution_hint([a,b], [True,True])
+                self.assertTrue(slv.solve(**args)) # should also work with an UNSAT hint
+
+            except NotSupportedError:
+                continue
+
+